Appellant Ronald Sorensen (the father) appeals from the district court’s order in favor of Appellee Sherri May (the mother) which denied his request to modify the parties’ divorce decree with respect to custody of their minor children and child support.
We affirm.
ISSUES
The father presents two issues on appeal:
1. Did the district court err in finding no substantial change of circumstances when there was an undisputed defacto change in custody of the minor children?
2. Did the district court err in failing to apply the child support guidelines when there was a substantial change of circumstances?
FACTS
The parties were granted a divorce in December of 1993. The divorce decree provided for the parties to have joint custody of their two minor children with each party having physical custody of the children for six months out of every year. The parties’ son was seventeen years old and their daughter was fourteen years old when the divorce decree was entered. According to the child *431support guidelines, the mother was entitled to receive a presumptive monthly support payment of $88.89 from the father. Each party agreed, however, to waive the support payments from the other.
At the time of the divorce, the children were living with their father in Cheyenne and commuting to school in Albin. After the decree was entered, the father and the children moved to Albin so that the children would not have to commute to school. The children did not go to live with their mother, who lived in Cheyenne, after they had stayed six months with their father.
On February 2, 1995, the father filed a petition to modify the provisions of the divorce decree which pertained to custody of the minor children and child support. He contended that a substantial change of circumstances had occurred because the children did not spend one-half of the year with their mother as was contemplated by the divorce decree. The father prayed for permanent and physical custody of the children and for child support in accordance with the child support guidelines.
After numerous delays and continuances, the district court held a hearing on August 21, 1996, to consider the father’s petition. Between the time that the divorce decree was entered and the time that the hearing was held, the son turned eighteen and graduated from high school. Consequently, the hearing focused primarily on the custody of the parties’ daughter.
At the conclusion of the hearing, the district court found in pertinent part:
Well, it appears that the best interest of the children ha[s] been admirably served all along here. I don’t see where it would be in their best interest to do any change, because thanks to the very mature and responsible way these two parents have acted vis-a-vis their daughter, it appears to me it wouldn’t necessarily be in her best interest for any change of custody, nor would it be at any time because she was enjoying a relationship with her father and her mother, which is one of the chief goals in any custody and visitation situation.
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... [I]t occurs to me that [the father] and [the mother] have acted in a very admirable and honorable fashion here, contrary to the situation that one sees in the District Court way too often....
Here the parties very realistically and responsibly recognize that ... the children w[ill] be attending school in Albin, as they were at the time of the divorce. And since it was their obvious preference to live in Albin rather than commute, I think that situation should be allowed to continue.
[The father] certainly gave notice when he filed this petition in February of ... ’95 that he was dissatisfied with that situation from only the point of view that he was not receiving contributions of support. The other side of it is that these parties mutually waived support at the time of the decree; they contemplated at the time that [the father] would be moving to Albin, which he did; that the children would be living there for that reason much of the time, which they did. Much to his credit, he never insisted that the children actually move.
The district court determined that a substantial change of circumstances did not occur and denied the father’s petition to modify the divorce decree. This appeal followed.
DISCUSSION
The father contends that the district court erred by ruling that he did not meet his burden of showing that a material or substantial change of circumstances occurred after the divorce decree was entered. The mother maintains that the district court did not abuse its discretion by refusing to modify the divorce decree.
The district court retains continuing jurisdiction to modify a divorce decree. W.S. 20-2-113(a) (amended 1997)1; Rocha v. *432Rocha, 925 P.2d 231, 233 (Wyo.1996). “A district court’s decision to modify a divorce decree is reviewed for [an] abuse of discretion.” 925 P.2d at 233. “Judicial discretion is a composite of many things, among which are conclusions drawn from objective criteria; it means a sound judgment exercised with regard to what is right under the circumstances and without doing so arbitrarily or capriciously.” Martin v. State, 720 P.2d 894, 897 (Wyo.1986). “A court does not abuse its discretion unless it acts in a manner which exceeds the bounds of reason under the circumstances. In determining whether there has been an abuse of discretion, the ultimate issue is whether or not the court could [have] reasonably conclude[d] as it did.” Duffy v. State, 730 P.2d 754, 757-58 (Wyo.1986).
A party who is seeking to modify the child custody provisions of a divorce decree has the burden of showing that
a substantial or material change in circumstances which affects the child’s welfare occurred subsequent to the entry of the initial decree, that the change warrants modification of the decree, and that the modification will be in the child’s best interests .... In order to decide whether a showing of material or substantial change in circumstances has been made, we examine the record to determine whether the district court could [have] reasonably conclude[d] from the evidence that such a change occurred.
Wilcox-Elliott v. Wilcox, 924 P.2d 419, 421 (Wyo.1996). See also Rocha, 925 P.2d at 233. A condition which existed when the divorce decree was entered is not a substantial or material change of circumstances that warrants modification of the decree. Crawford v. Crawford, 828 P.2d 1192, 1193 (Wyo.1992). In Gurney v. Gurney, 899 P.2d 52, 54-55 (Wyo.1995), this Court recognized that, because parents must work closely together in joint custody arrangements, it may be easier to reopen a divorce decree which contains a joint custody provision. We decided that, because both parties agreed the joint custody situation was not working, the district court erred by not reopening the case. 899 P.2d at 55. •
At the time of the divorce in this case, the children were going to school in Albin. Both parties testified that they did not want the children to commute from Cheyenne to Albin. The father acknowledged that he was not sure when the divorce decree was entered whether “it [was] anticipated they would spend the other half of the year with their mother.” Taking this evidence into account, the district court concluded that the parties had foreseen at the time of the divorce that they would not strictly adhere to the provision which declared that the children would spend six months out of every year with each parent. Even though they knew that the custody provision might not be followed exactly, the parties agreed to waive all child support obligations. Unlike in the Gurney case, the parties here did not agree that the joint custody arrangement was not working. In fact, the mother contested the father’s request for a modification.
This Court stated in Gurney:
We recognize a measure of instability is inherent in a joint custody order because it requires two parents, who are not residing together, to share custodial rights and responsibilities and resolve the logistics of caring for the child.
... The premise of the joint custody order is the parents’ ability to resolve between themselves the custodial details. There can be little question that joint custody requires sincere dedication on the part of each parent to safeguard the security and stability vital to a child’s best interest.
899 P.2d at 55 (citations omitted). Here, the district court commended the parties for working together in the best interests of their children. The parties agreed that it was best for the children to live in Albin since they went to school there. If the children had moved in with their mother after six months, they would have had to commute again. The district court, therefore, did not abuse its discretion when it concluded that the father did not satisfy his burden of proving that a material or substantial change of circumstances had occurred subsequent to *433the entry of the divorce decree. The flexibility of the joint custody arrangement allowed these parents to amicably work together to meet the children’s needs. We expect the parties to continue to work together for the best interests of their children.
Affirmed.
. Prior to being amended in 1997, W.S. 20-2-113(a) provided in pertinent part:
(a) ... The court which entered the decree has continuing subject matter and personal jurisdiction to enforce or revise the decree concerning the care, custody, visitation and maintenance of the children as the circum*432stances of the parents and the benefit of the children require[].